Methods for cementing in a subterranean formation using a cement composition containing calcium silicate hydrate seeds

ABSTRACT

According to an embodiment, a method of cementing in a subterranean formation comprises: introducing a cement composition into the subterranean formation, wherein the cement composition comprises: cement; water; and calcium silicate hydrate (C-S-H) seeds, wherein a test cement composition consisting essentially of: the cement; the water; and the C-S-H seeds, and in the same proportions as in the cement composition, develops a compressive strength of at least 1,200 psi (8.3 MPa) when tested at 24 hours, a temperature of 60° F. (15.6° C.), and a pressure of 3,000 psi (20.7 MPa); and allowing the cement composition to set. According to another embodiment, the C-S-H seeds are mesoscopic particles, nanoparticles, or combinations thereof, and wherein the C-S-H seeds are in a concentration in the range of about 1% to about 5% by weight of the cement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/425,535, filed Dec. 21, 2010.

TECHNICAL FIELD

Methods of cementing in a subterranean formation are provided. Thecement compositions for use in the subterranean formation includemesoscopic particles, nanoparticles, or combinations thereof of calciumsilicate hydrate (C-S-H) seeds. In an embodiment, the cement compositionalso includes a latex additive. In another embodiment, the subterraneanformation is penetrated by a well.

SUMMARY

According to an embodiment, a method of cementing in a subterraneanformation comprises: introducing a cement composition into thesubterranean formation, wherein the cement composition comprises:cement; water; and calcium silicate hydrate (C-S-H) seeds, wherein atest cement composition consisting essentially of: the cement; thewater; and the C-S-H seeds, and in the same proportions as in the cementcomposition, develops a compressive strength of at least 1,200 psi (8.3MPa) when tested at 24 hours, a temperature of 60° F. (15.6° C.), and apressure of 3,000 psi (20.7 MPa); and allowing the cement composition toset.

According to another embodiment, a method of cementing in a subterraneanformation comprises: introducing a cement composition into thesubterranean formation, wherein the cement composition comprises:cement; water; and calcium silicate hydrate (C-S-H) seeds, wherein theC-S-H seeds are in at least a sufficient concentration such that thecement composition develops a compressive strength of at least 1,200 psi(8.3 MPa) when tested at 24 hours, a temperature of 60° F. (15.6° C.),and a pressure of 3,000 psi (20.7 MPa), whereas a substantiallyidentical cement composition without the C-S-H seeds, develops acompressive strength of less than 1,200 psi (8.3 MPa) when tested at 24hours, a temperature of 60° F. (15.6° C.), and a pressure of 3,000 psi(20.7 MPa); and allowing the cement composition to set.

According to another embodiment, a method of cementing in a subterraneanformation comprises: introducing a cement composition into thesubterranean formation, wherein the cement composition comprises:cement; water; and calcium silicate hydrate (C-S-H) seeds, wherein theC-S-H seeds are mesoscopic particles, nanoparticles, or combinationsthereof, and wherein the C-S-H seeds are in a concentration in the rangeof about 1% to about 5% by weight of the cement; and allowing the cementcomposition to set.

BRIEF DESCRIPTION OF THE FIGURE

The features and advantages of certain embodiments will be more readilyappreciated when considered in conjunction with the accompanying figure.The figure is not to be construed as limiting any of the preferredembodiments.

FIG. 1 is a graph of consistency (Bc) versus time (hr:min:sec) showingthe thickening time at a temperature of 60° F. (15.6° C.) and a pressureof 5,000 psi (34.5 MPa) for four different cement compositions having adensity of 15.8 pounds per gallon (ppg) (1.9 kilograms per liter(kg/l)). The cement compositions contained: Class G cement; deionized(DI) water; 0.05 gallons per sack of cement (gal/sk) D-AIR 3000L™defoaming agent; and varying concentrations of C-S-H seeds. The C-S-Hseeds were X-SEED® 100, obtained from BASF.

DETAILED DESCRIPTION

As used herein, the words “comprise,” “have,” “include,” and allgrammatical variations thereof are each intended to have an open,non-limiting meaning that does not exclude additional elements or steps.

As used herein, the words “consisting essentially of,” and allgrammatical variations thereof are intended to limit the scope of aclaim to the specified materials or steps and those that do notmaterially affect the basic and novel characteristic(s) of the claimedinvention. For example, a test cement composition can consistessentially of cement, water, and C-S-H seeds. The test cementcomposition can include other ingredients so long as the presence of theother ingredients do not materially affect the basic and novelcharacteristics of the claimed invention.

As used herein, a “fluid” is a substance having a continuous phase thattends to flow and to conform to the outline of its container when thesubstance is tested at a temperature of 71° F. (22° C.) and a pressureof one atmosphere “atm” (0.1 megapascals “MPa”). A fluid can be a liquidor gas. A homogenous fluid has only one phase, whereas a heterogeneousfluid has more than one distinct phase. A colloid is an example of aheterogeneous fluid. A colloid can be: a slurry, which includes acontinuous liquid phase and undissolved solid particles as the dispersedphase; an emulsion, which includes a continuous liquid phase and atleast one dispersed phase of immiscible liquid droplets; or a foam,which includes a continuous liquid phase and a gas as the dispersedphase.

As used herein, a “cement composition” is a mixture of at least cementand water. A cement composition can include additives. As used herein,the term “cement” means an initially dry substance that, in the presenceof water, acts as a binder to bind other materials together. An exampleof cement is Portland cement. A cement composition is generally a slurryin which the water is the continuous phase of the slurry and the cement(and any other insoluble particles) is the dispersed phase. Thecontinuous phase of a cement composition can include dissolved solids.

Oil and gas hydrocarbons are naturally occurring in some subterraneanformations. A subterranean formation containing oil or gas is sometimesreferred to as a reservoir. A reservoir may be located under land or offshore. Reservoirs are typically located in the range of a few hundredfeet (shallow reservoirs) to a few tens of thousands of feet (ultra-deepreservoirs). In order to produce oil or gas, a wellbore is drilled intoa reservoir or adjacent to a reservoir.

A well can include, without limitation, an oil, gas, water, or injectionwell. As used herein, a “well” includes at least one wellbore. Awellbore can include vertical, inclined, and horizontal portions, and itcan be straight, curved, or branched. As used herein, the term“wellbore” includes any cased, and any uncased, open-hole portion of thewellbore. A near-wellbore region is the subterranean material and rockof the subterranean formation surrounding the wellbore. As used herein,a “well” also includes the near-wellbore region. The near-wellboreregion is generally considered to be the region within about 100 feet ofthe wellbore. As used herein, “into a well” means and includes into anyportion of the well, including into the wellbore or into thenear-wellbore region via the wellbore.

A portion of a wellbore may be an open hole or cased hole. In anopen-hole wellbore portion, a tubing string may be placed into thewellbore. The tubing string allows fluids to be introduced into orflowed from a remote portion of the wellbore. In a cased-hole wellboreportion, a casing is placed into the wellbore which can also contain atubing string. A wellbore can contain an annulus. Examples of an annulusinclude, but are not limited to: the space between the wellbore and theoutside of a tubing string in an open-hole wellbore; the space betweenthe wellbore and the outside of a casing in a cased-hole wellbore; andthe space between the inside of a casing and the outside of a tubingstring in a cased-hole wellbore.

During well completion, it is common to introduce a cement compositioninto an annulus in a wellbore. For example, in a cased-hole wellbore, acement composition can be placed into and allowed to set in an annulusbetween the wellbore and the casing in order to stabilize and secure thecasing in the wellbore. By cementing the casing in the wellbore, fluidsare prevented from flowing into the annulus. Consequently, oil or gascan be produced in a controlled manner by directing the flow of oil orgas through the casing and into the wellhead. Cement compositions canalso be used in primary or secondary cementing operations,well-plugging, squeeze cementing, or gravel packing operations.

Cement generally contains four main types of minerals. Cement can alsoinclude other minerals in addition to the four main types. The mineralsin cement are commonly referred to as the phases of the cement. The fourmain phases of cement are called alite, belite, aluminate, and ferrite.

“Alite” is a name for tricalcium silicate and “belite” is a name fordicalcium silicate. Cement chemist often abbreviate alite as C₃S andbelite as C₂S. Both, alite and belite have different compositionscompared to pure tricalcium silicate and dicalcium silicate because eachone contains minor amounts of other oxides besides calcium oxide (CaO)and silicon dioxide (SiO₂).

“Aluminate” is a name for tricalcium aluminate, abbreviated by cementchemists as C₃A. Aluminate has a different composition compared to puretricalcium aluminate because it contains minor amounts of other oxidesbesides CaO and aluminum oxide (Al₂O₃). “Ferrite” is a name fortetracalcium aluminoferrite, abbreviated by cement chemists as C₄AF.Ferrite has a different composition compared to pure tetracalciumaluminoferrite because it contains minor amounts of other oxides besidesCaO, Al₂O₃, and iron oxide (Fe₂O₃).

When cement is mixed with water, the various phases of the cement canundergo a hydration reaction and form hydration products. The silicatephases (alite and belite) form hydration products of at least calciumsilicate hydrate and calcium hydroxide (abbreviated by cement chemistsas CH). Calcium silicate hydrate is often abbreviated as C-S-H. Thedashes indicate there is no strict ratio of CaO to SiO₂ inferred. Thealuminate and ferrite phases can form a variety of hydration products,including, hydrogarnet, ettringite, and monosulfoaluminate, depending onthe amount of gypsum present in the cement.

Soon after mixing cement with water, aluminate reacts very quickly withthe water to form an aluminate-rich gel. This reaction is highlyexothermic, but generally lasts for only a few minutes after mixing.This stage in the hydration reaction is normally followed by a few hoursof relatively low heat evolution, sometimes called the dormant stage.The dormant stage is when a cement composition can be placed in thelocation to be cemented. Eventually, the cement composition becomes tooviscous to place in the desired location. At the end of the dormantstage, the alite and belite start to react with the water to form theirhydration products. The hydration products occupy a larger volume in thecement composition compared to the solid phases. Consequently, thecement composition is converted from a viscous slurry into a rigid solidmaterial. C-S-H can represent up to 70% by volume of the cementcomposition matrix and is primarily what gives the cement compositionits mechanical properties, such as compressive strength.

Each phase of the cement generally reacts at a different rate to formtheir hydration products. Some of the factors that can influence thereaction rate of the various phases of the cement and water include: thetype of the reactant; the physical state of the reactants; theconcentration of the reactants in relation to each other; andtemperature. The four main phases of cement have the following order ofreaction rates based solely on the type of the reactant: aluminate(C₃A)>alite (C₃S)>belite (C₂S) and ferrite (C₄AF). For example, alitehydrates and hardens rapidly and is responsible for the initial settingand early compressive strength of a cement composition. By contrast,belite hydrates and hardens more slowly and contributes to thedevelopment of compressive strength of the cement composition at a latertime (normally beyond 7 days after mixing).

The physical state of the reactants can also affect the reaction rate.When the reactants are in different phases, i.e., a solid, liquid, orgas, then the reaction rate is limited to the interface between thereactants. For example, alite is a solid, and when mixed with liquidwater, the surface area of the alite plays a role in the reaction ratebetween the alite and the water. By increasing the surface area of asolid, such as alite, in a liquid phase, the reaction rate can beincreased.

The concentration of reactants and temperature can also affect thereaction rate. Generally, as the concentration of one of the reactantsincreases, the reaction rate also increases. Moreover, as temperatureincreases, the reaction rate generally increases. However, there isusually a maximum increase in the reaction rate, such that, at somepoint, the reaction rate no longer increases even though theconcentration of a reactant or the temperature is being increased.

Solid particles can broadly be described as falling within the followingsize ranges: bulk particles; mesoscopic particles; and nanoparticles. Asused herein, a “bulk particle” is a particle having a particle size ofgreater than 1 micrometer (1 μm or 1 micron). As used herein, a“mesoscopic particle” is a particle having a particle size in the rangeof 1 micron to 0.1 micron. As used herein, a “nanoparticle” is aparticle having a particle size of less than 0.1 micron. As used herein,the term “particle size” refers to the volume surface mean diameter(“D_(s)”), which is related to the specific surface area of theparticle. The volume surface mean diameter may be defined by thefollowing equation: D_(s)=6/(Φ_(s)A_(w)ρ_(p)), where Φ_(s)=sphericity;A_(w)=specific surface area; and ρ_(p)=particle density. Due to theirsmall size, the manufacture of nanoparticles can be quite costly. Bycontrast, mesoscopic particles can cost less to manufacture. In order toreduce the cost associated with cementing operations, additives that aremesoscopic particles may be preferred over nanoparticles.

The size of a particle can influence the particle's physical properties.For example, as the size of a system of particles decreases below thesize of bulk particles, the more changes in the particle's physicalproperties can occur. This is known as the quantum size effect. Thequantum size effect means that the physical properties of solids changeswith greater reductions in particle size. The quantum size effectbecomes dominant in nanoparticles; however, the quantum size effect canalso be observed with mesoscopic particles as well. The quantum sizeeffect is normally not observed for bulk particles. One example of achange in physical properties is an increase in the surface area tovolume ratio of the particles. This increase in the surface area tovolume ratio creates a higher surface energy for the particles. Thishigher surface energy means that more contact is made between theparticles and a reactant, resulting in a higher rate of reaction betweenthe particles and the reactant. For a cement composition, a highersurface energy enables the phases of the cement to react at a fasterrate, thereby enhancing some of the physical properties of the cementcomposition, for example, thickening time or compressive strength.

During cementing operations, it is desirable for the cement compositionto remain pumpable during introduction into the subterranean formationand until the cement composition is situated in the portion of thesubterranean formation to be cemented. After the cement composition hasreached the portion of the subterranean formation to be cemented, thecement composition can ultimately set. A cement composition thatthickens too quickly while being pumped can damage pumping equipment orblock tubing or pipes. A cement composition that sets too slowly cancost time and money while waiting for the composition to set.

If any test (e.g., thickening time or compressive strength) requires thestep of mixing, then the cement composition is “mixed” according to thefollowing procedure. The water is added to a mixing container and thecontainer is then placed on a mixer base. The motor of the base is thenturned on and maintained at 4,000 revolutions per minute (rpm). Thecement and any other ingredients are added to the container at a uniformrate in not more than 15 seconds (s). After all the cement and any otheringredients have been added to the water in the container, a cover isthen placed on the container, and the cement composition is mixed at12,000 rpm (+/−500 rpm) for 35 s (+/−1 s). It is to be understood thatthe cement composition is mixed at ambient temperature and pressure(about 71° F. (22° C.) and about 1 atm (0.1 MPa)).

It is also to be understood that if any test (e.g., thickening time orcompressive strength) requires the test be performed at a specifiedtemperature and possibly a specified pressure, then the temperature andpressure of the cement composition is ramped up to the specifiedtemperature and pressure after being mixed at ambient temperature andpressure. For example, the cement composition can be mixed at 71° F.(22° C.) and 1 atm (0.1 MPa) and then placed into the testing apparatusand the temperature of the cement composition can be ramped up to thespecified temperature. As used herein, the rate of ramping up thetemperature is in the range of about 3° F./min to about 5° F./min (about1.67° C./min to about 2.78° C./min). After the cement composition isramped up to the specified temperature and possibly specified pressure,the cement composition is maintained at that temperature and pressurefor the duration of the testing.

As used herein, the “thickening time” is how long it takes for a cementcomposition to become unpumpable at a specified temperature andpressure. The pumpability of a cement composition is related to theconsistency of the composition. The consistency of a cement compositionis measured in Bearden units of consistency (Bc), a dimensionless unitwith no direct conversion factor to the more common units of viscosity.As used herein, a cement composition becomes “unpumpable” when theconsistency of the composition reaches 70 Bc. As used herein, theconsistency of a cement composition is measured as follows. The cementcomposition is mixed. The cement composition is then placed in the testcell of a High-Temperature, High-Pressure (HTHP) consistometer, such asa FANN® Model 275 or a Chandler Model 8240. Consistency measurements aretaken continuously until the cement composition exceeds 70 Bc.

A cement composition can develop compressive strength. Cementcomposition compressive strengths can vary from 0 psi to over 10,000 psi(0 to over 69 MPa). Compressive strength is generally measured at aspecified time after the composition has been mixed and at a specifiedtemperature and pressure. Compressive strength can be measured, forexample, at a time of 24 hours. The non-destructive compressive strengthmethod continually measures correlated compressive strength of a cementcomposition sample throughout the test period by utilizing anon-destructive sonic device such as an Ultrasonic Cement Analyzer (UCA)available from FANN® Instruments in Houston, Tex., USA. As used herein,the “compressive strength” of a cement composition is measured using thenon-destructive method at a specified time, temperature, and pressure asfollows. The cement composition is mixed. The cement composition is thenplaced in an Ultrasonic Cement Analyzer and tested at a specifiedtemperature and pressure. The UCA continually measures the transit timeof the acoustic signal through the sample. The UCA device containspreset algorithms that correlate transit time to compressive strength.The UCA reports the compressive strength of the cement composition inunits of pressure, such as psi or MPa.

The compressive strength of a cement composition can be used to indicatewhether the cement composition has initially set or set. As used herein,a cement composition is considered “initially set” when the cementcomposition develops a compressive strength of 50 psi (0.3 MPa) at aspecified temperature and pressure. As used herein, the “initial settingtime” is the difference in time between when the cement and any otheringredients are added to the water and when the composition is initiallyset.

As used herein, the term “set,” and all grammatical variations thereof,are intended to mean the process of becoming hard or solid by curing. Asused herein, the “setting time” is the difference in time between whenthe cement and any other ingredients are added to the water and when thecomposition has set at a specified temperature. It can take up to 48hours or longer for a cement composition to set. Some cementcompositions can continue to develop compressive strength over thecourse of several days. The compressive strength of a cement compositioncan reach over 10,000 psi (69 MPa).

In order to help enhance some of the physical or mechanical propertiesof a cement composition, C-S-H seeds can be added to a cementcomposition. As used herein, “C-S-H seeds” means solid particles ofC-S-H and does not include any C-S-H formed from the hydration reactionof any of the phases of the cement and the water in the cementcomposition. By adding C-S-H seeds to a cement composition, the C-S-Hseeds provide extra nuclei to the phases of the cement, therebyincreasing the hydration reaction rates of the phases. By increasing thehydration reaction rates, some of the properties of the cementcomposition can be enhanced. For example, the initial setting time andsetting time of a cement composition containing C-S-H seeds can bedecreased.

One of the purposes of a cementing operation can be to isolate a portionof a wellbore and prevent the flow of fluids through the cementcomposition into other areas of the wellbore. An example of fluid flowthrough a cement composition is called gas migration. Gas migration iscaused by a loss in hydrostatic pressure at some time before the cementcomposition has achieved a high enough static gel strength to resist gasflow through the cement composition.

Static gel strength is the development of rigidity within the matrix ofa cement composition that causes the cement composition to resist aforce placed upon it. A cement composition with a static gel strength ofless than 100 lb/100 ft² is relatively fluid and can flow and transferhydrostatic pressure. The static gel strength of a cement compositioncan be measured using a variety of testing equipment. The static gelstrength of a cement composition is usually reported in units of weightper unit area, such as pounds per square feet (1 b/ft²).

As used herein, the “SGSA static gel strength” of a cement compositionis measured as follows. The cement composition is mixed. The cementcomposition is then placed in a Static Gel Strength Analyzer (SGSA),such as a Chandler SGSA, and tested at a specified temperature andpressure. The SGSA continually measures the transit time of the acousticsignal through the sample. The SGSA device contains preset algorithmsthat correlate transit time to static gel strength.

As used herein, the “Mini MACS static gel strength” (Mini MultipleAnalysis Cement System) of a cement composition is measured as follows.The cement composition is mixed. The cement composition is then placedinto a Mini MACS Analyzer. The cement composition is heated to aspecified temperature, and pressurized to a specified pressure andstirred at 150 revolutions per minute (rpm) until the anticipatedplacement time is reached. The paddle of the Mini MACS Analyzer isrotated at a speed of 0.2°/min and the shear resistance on the paddle ismeasured. The shear resistance on the paddle is then correlated to thestatic gel strength of the cement composition.

As used herein, the “zero gel time” is the difference in time betweenwhen a cement composition is mixed and when the cement compositionreaches a static gel strength of 100 lb/100 ft². After reaching 100lb/100 ft², a cement composition can continue to develop static gelstrength. When the cement composition develops a static gel strength ofat least 500 lb/100 ft², the cement composition generally no longerloses hydrostatic pressure, and as such, gas migration can either begreatly diminished or can cease altogether. As used herein, the“transition time” is the time it takes for the static gel strength of acement composition to increase from 100 lb/100 ft² to 500 lb/100 ft². Itis desirable to have as short a transition time as possible.

An additive can be included in a cement composition to help eliminate orcontrol gas migration. An example, of such an additive is latex. Latexis a slurry consisting of solid rubber particles as the dispersed phaseand a liquid as the continuous phase. Generally, water is the continuousphase of the slurry. Examples of suitable rubber particles, includenatural rubber (cis-1,4-polyisoprene) in most of its modified types, andsynthetic polymers of various types, including styrene-butadiene rubber(SBR), cis-1,4-polybutadiene rubber and blends thereof with naturalrubber or styrene-butadiene rubber, high styrene resin, butyl rubber,ethylene-propylene rubbers (EPM and EPDM), neoprene rubber, nitrilerubber, cis-1,4-polyisoprene rubber, silicone rubber, chlorosulfonatedpolyethylene rubber, crosslinked polyethylene rubber, epichlorohydrinrubber, fluorocarbon rubber, fluorosilicone rubber, polyurethane rubber,polyacrylic rubber, polysulfide rubber, AMPS-styrene-butadiene rubber,and combinations thereof. “AMPS” refers to2-acrylamido-2-methylpropanesulfonic acid or salts thereof. Examples ofsuitable latex additives can be found in: U.S. Pat. No. 5,293,938 issuedto David D. Onan, Garland W. Davis, Roger S. Cromwell, and Wendell D.Riley on Mar. 15, 1994; U.S. Pat. No. 5,688,844 issued to JitenChatterji, Bobby J. King, Patty L. Totten, and David D. Onan on Nov. 18,1997; and U.S. Pat. No. 7,784,542 B2 issued to Craig W. Roddy, JitenChatterji, Roger Cromwell, Rahul Chandrakant Patil, Abhijit Tarafdar,Abhimanyu Deshpande, and Christopher Lynn Gordon on Aug. 31, 2010, eachof which is hereby incorporated by reference in its entirety for allpurposes. It is common to include other additives in a cementcomposition containing a latex additive. For example, vulcanizing agentsfor the rubber and latex stabilizers can be added to the cementcomposition. Examples of suitable vulcanizing agents include, sulfur,organic peroxide compounds, azo compounds, phenolic curatives,benzoquinone derivatives, bismaleimides, selenium, tellurium, nitrocompounds, resins, metal oxides, and organic sulfur compounds such asalkyl thiuram disulfides, which can be found in U.S. Pat. No. 5,293,938.Examples of suitable latex stabilizers include, ethoxylated nonylphenolcontaining in the range of 15 from about 15 to about 40 moles ofethylene oxide and the sodium salt of a sulfonated and ethoxylatedcompound having the formula H(CH₂)₁₂₋₁₅, which can be found in U.S. Pat.No. 5,688,844.

However, some additives used to accelerate the setting of a cementcomposition can adversely interact with a latex additive. As a result,cement compositions containing a latex additive and a set acceleratormay have reduced compressive strength and may develop compressivestrength or static gel strength more slowly. Moreover, cementcompositions containing a latex additive may have reduced compressivestrength and may develop compressive strength or static gel strengthmore slowly compared to a similar cement composition without the latexadditive.

It has been discovered that a cement composition containing C-S-H seeds,wherein the C-S-H seeds are mesoscopic particles, nanoparticles, or acombination thereof, can be used in a subterranean formation. It hasalso been discovered that a cement composition containing C-S-H seeds,wherein the C-S-H seeds are mesoscopic particles, nanoparticles, or acombination thereof, can be used in cement compositions containing alatex additive. Some of the advantages of including the C-S-H seeds in acement composition, is that the cement composition can: develop a highercompressive strength; have a shorter initial setting time and settingtime; develop a higher static gel strength; and be compatible withcement additives commonly used in cementing operations, compared to asimilar cement composition without the C-S-H seeds.

According to an embodiment, a method of cementing in a subterraneanformation comprises: introducing a cement composition into thesubterranean formation, wherein the cement composition comprises:cement; water; and calcium silicate hydrate (C-S-H) seeds, wherein atest cement composition consisting essentially of: the cement; thewater; and the C-S-H seeds, and in the same proportions as in the cementcomposition, develops a compressive strength of at least 1,200 psi (8.3MPa) when tested at 24 hours, a temperature of 60° F. (15.6° C.), and apressure of 3,000 psi (20.7 MPa); and allowing the cement composition toset.

According to another embodiment, a method of cementing in a subterraneanformation comprises: introducing a cement composition into thesubterranean formation, wherein the cement composition comprises:cement; water; and calcium silicate hydrate (C-S-H) seeds, wherein theC-S-H seeds are in at least a sufficient concentration such that thecement composition develops a compressive strength of at least 1,200 psi(8.3 MPa) when tested at 24 hours, a temperature of 60° F. (15.6° C.),and a pressure of 3,000 psi (20.7 MPa), whereas a substantiallyidentical cement composition without the C-S-H seeds, develops acompressive strength of less than 1,200 psi (8.3 MPa) when tested at 24hours, a temperature of 60° F. (15.6° C.), and a pressure of 3,000 psi(20.7 MPa); and allowing the cement composition to set.

According to another embodiment, a method of cementing in a subterraneanformation comprises: introducing a cement composition into thesubterranean formation, wherein the cement composition comprises:cement; water; and calcium silicate hydrate (C-S-H) seeds, wherein theC-S-H seeds are mesoscopic particles, nanoparticles, or combinationsthereof, and wherein the C-S-H seeds are in a concentration in the rangeof about 1% to about 5% by weight of the cement; and allowing the cementcomposition to set.

The discussion of preferred embodiments regarding the cement compositionor any ingredient in the cement composition, is intended to apply to allof the method embodiments. The discussion of preferred embodimentsregarding the cement composition or any ingredient in the cementcomposition, is intended to apply to the cement composition, includingany additional additives that might be included in the cementcomposition. For example, if the cement composition includes a latexadditive, then the discussion of preferred embodiments, is meant toapply to a cement composition without a latex additive and a cementcomposition including the latex additive. It is to be understood thatfor any preferred embodiment given for a physical/mechanical property ofthe cement composition (e.g., thickening time, setting time, ortransition time), then the C-S-H seeds should be in at least asufficient concentration and the particle size of the C-S-H seeds shouldbe chosen such that the cement composition develops the preferredphysical/mechanical property.

Any reference to the unit “gallons” means U.S. gallons. As used herein,the term “soluble” means that at least 1 part of the substance dissolvesin 99 parts of the liquid at a temperature of 77° F. (25° C.) and apressure of 1 atm (0.1 MPa). As used herein, the term “insoluble” meansthat less than 1 part of the substance dissolves in 99 parts of theliquid at a temperature of 77° F. (25° C.) and a pressure of 1 atm (0.1MPa).

The cement composition includes cement. The cement can be a hydrauliccement. A variety of hydraulic cements may be utilized in accordancewith the present invention, including, but not limited to, thosecomprising calcium, aluminum, silicon, oxygen, iron, and/or sulfur,which set and harden by a reaction with water. Suitable hydrauliccements include, but are not limited to, Portland cements, pozzolanacements, gypsum cements, high alumina content cements, slag cements,silica cements, and combinations thereof. In certain embodiments, thehydraulic cement may comprise a Portland cement. In some embodiments,the Portland cements that are suited for use in the present inventionare classified as Classes A, C, H, and G cements according to AmericanPetroleum Institute, API Specification for Materials and Testing forWell Cements, API Specification 10, Fifth Ed., Jul. 1, 1990. Preferably,the cement is Class G or Class H cement.

The cement composition includes water. The water can be selected fromthe group consisting of freshwater, brackish water, saltwater, and anycombination thereof. The cement composition can further include awater-soluble salt. Preferably, the salt is selected from sodiumchloride, calcium chloride, calcium bromide, potassium chloride,potassium bromide, magnesium chloride, and any combination thereof. Thecement composition can contain the water-soluble salt in a concentrationin the range of about 5% to about 35% by weight of the water (ww).

The cement composition includes calcium silicate hydrate (C-S-H) seeds.Preferably, the C-S-H seeds are insoluble in water. The C-S-H seeds canbe synthetic or the product of a hydration reaction between alite orbelite and water. The dashes (−) indicate that no particular ratio ofcalcium (C) to silicate (5) is intended. However, a common ratio of C:Sin calcium silicate hydrate is 2:1. The ratio of C:S can be any ratio solong as the calcium silicate hydrate enables the cement composition tosatisfy the preferred embodiments. Preferably, the ratio of C:S is inthe range of 0.5:2 to 2.5:0.5.

In one embodiment, the C-S-H seeds are mesoscopic particles,nanoparticles, or combinations thereof. Preferably, the C-S-H seeds aremesoscopic particles. According to this preferred embodiment, the C-S-Hseeds have a particle size distribution such that at least 90% of theC-S-H seeds have a particle size in the range of 1 micron to 0.1microns. More preferably, the C-S-H seeds have a particle sizedistribution such that at least 90% of the C-S-H seeds have a particlesize in the range of about 0.4 microns to 0.1 microns.

The C-S-H seeds can be in a dry form. The C-S-H seeds can also be in aslurry form, in which the C-S-H seeds are the dispersed phase and anaqueous liquid or a liquid hydrocarbon is the continuous phase of theslurry. A commercially available example of C-S-H seeds in a slurry formis X-SEED® 100, available from BASF in Trostberg, Germany.

In one embodiment, the C-S-H seeds are in a concentration of at least0.05% by weight of the cement (bwc). It should be understood that theconcentrations of the C-S-H seeds are provided based on the dry weightof the C-S-H seeds. If the C-S-H seeds are in a slurry form, then theslurry will have a particular active solid % of the C-S-H seeds. Forexample, in a slurry, the dry weight concentration of C-S-H seeds can becalculated based on the active solid content of the C-S-H seeds in theslurry. In another embodiment, the C-S-H seeds are in a concentration inthe range of about 0.05% to about 7% bwc. In another embodiment, theC-S-H seeds are in a concentration in the range of about 1% to about 5%bwc. According to another embodiment, the C-S-H seeds are in at least asufficient concentration such that the cement composition develops acompressive strength of at least 1,200 psi (8.3 MPa) when tested at 24hours, a temperature of 60° F. (15.6° C.), and a pressure of 3,000 psi(20.7 MPa), whereas a substantially identical cement composition,without the C-S-H seeds, develops a compressive strength of less than1,200 psi (8.3 MPa) when tested at 24 hours, a temperature of 60° F.(15.6° C.), and a pressure of 3,000 psi (20.7 MPa).

In one embodiment, the cement composition further comprises a latexadditive. In an embodiment, the latex additive is a slurry containingsolid rubber particles as the dispersed phase and a liquid as thecontinuous phase. Water can be the continuous phase of the slurry.Examples of suitable rubber particles, include natural rubber(cis-1,4-polyisoprene) in most of its modified types, and syntheticpolymers of various types, including styrene-butadiene rubber (SBR),cis-1,4-polybutadiene rubber and blends thereof with natural rubber orstyrene-butadiene rubber, high styrene resin, butyl rubber,ethylene-propylene rubbers (EPM and EPDM), neoprene rubber, nitrilerubber, cis-1,4-polyisoprene rubber, silicone rubber, chlorosulfonatedpolyethylene rubber, crosslinked polyethylene rubber, epichlorohydrinrubber, fluorocarbon rubber, fluorosilicone rubber, polyurethane rubber,polyacrylic rubber, polysulfide rubber, AMPS-styrene-butadiene rubber,and combinations thereof. “AMPS” refers to2-acrylamido-2-methylpropanesulfonic acid or salts thereof. The cementcomposition can also include other additives in addition to the latexadditive. For example, vulcanizing agents for the rubber and latexstabilizers can be added to the cement composition. Examples of suitablevulcanizing agents include, sulfur, organic peroxide compounds, azocompounds, phenolic curatives, benzoquinone derivatives, bismaleimides,selenium, tellurium, nitro compounds, resins, metal oxides, and organicsulfur compounds such as alkyl thiuram disulfides. Examples of suitablelatex stabilizers include, ethoxylated nonylphenol containing in therange of from about 15 to about 40 moles of ethylene oxide and thesodium salt of a sulfonated and ethoxylated compound having the formulaH(CH₂)₁₂₋₁₅. Examples of suitable latex additives, ingredients in thelatex additive, and additional additives for a cement compositioncontaining the latex additive, such as rubber vulcanization additivesand latex stabilizer additives, can be found in U.S. Pat. Nos.5,293,938, 5,688,844, and U.S. Pat. No. 7,784,542 B2 (listed above),which are hereby incorporated by reference in their entirety for allpurposes. Suitable commercially-available examples of a latex additiveinclude, but are not limited to, LATEX 2000™ latex additive and LATEX3000™ latex additive, marketed by Halliburton Energy Services, Inc.

In an embodiment, the cement composition has a thickening time of atleast 2 hours at a temperature of 60° F. (15.6° C.) and a pressure of5,000 psi (34.5 MPa). In another embodiment, the cement composition hasa thickening time in the range of about 4 to about 15 hours at atemperature of 60° F. (15.6° C.) and a pressure of 5,000 psi (34.5 MPa).Some of the variables that can affect the thickening time of the cementcomposition include the concentration of the C-S-H seeds, theconcentration of any set retarder included in the cement composition,the concentration of any salt present in the cement composition, and thebottomhole temperature of the subterranean formation. As used herein,the term “bottomhole” refers to the portion of the subterraneanformation to be cemented. In another embodiment, the cement compositionhas a thickening time of at least 3 hours at the bottomhole temperatureand pressure of the subterranean formation.

In one embodiment, the cement composition has an initial setting time ofless than 24 hours, more preferably less than 12 hours, at a temperatureof 60° F. (15.6° C.) and a pressure of 3,000 psi (20.7 MPa). In anotherembodiment, the cement composition has an initial setting time of lessthan 24 hours, more preferably less than 12 hours, at the bottomholetemperature and pressure of the subterranean formation.

Preferably, the cement composition has a setting time of less than 48hours at a temperature of 60° F. (15.6° C.). More preferably, the cementcomposition has a setting time of less than 24 hours at a temperature of60° F. (15.6° C.). Most preferably, the cement composition has a settingtime in the range of about 3 to about 24 hours at a temperature of 60°F. (15.6° C.). In another embodiment, the cement composition has asetting time of less than 24 hours, more preferably less than 12 hours,at the bottomhole temperature and pressure of the subterraneanformation.

According to an embodiment, a test cement composition consistingessentially of: the cement; the water; and the C-S-H seeds, and in thesame proportions as in the cement composition, develops a compressivestrength of at least 1,200 psi (8.3 MPa) when tested at 24 hours, atemperature of 60° F. (15.6° C.), and a pressure of 3,000 psi (20.7MPa). Preferably, the cement composition has a compressive strength ofat least 500 psi (3.5 MPa) when tested at 24 hours, a temperature of 60°F. (15.6° C.), and a pressure of 3,000 psi (20.7 MPa). More preferably,the cement composition has a compressive strength in the range of about1,000 to about 5,000 psi (about 3.5 to about 34.5 MPa) when tested at 24hours, a temperature of 60° F. (15.6° C.), and a pressure of 3,000 psi(20.7 MPa). According to another embodiment, the cement composition hasa compressive strength in the range of about 1,000 to about 5,000 psi(about 3.5 to about 34.5 MPa) at the bottomhole temperature and pressureof the subterranean formation.

Preferably, the cement composition has a transition time of less than 4hours (hr), using the SGSA static gel strength procedure at atemperature of 155° F. (68.3° C.) and a pressure of 4,500 psi (31 MPa).In one embodiment, the C-S-H seeds are in at least a sufficientconcentration such that the cement composition has a transition time ofless than 4 hr, using the SGSA static gel strength procedure at atemperature of 155° F. (68.3° C.) and a pressure of 4,500 psi (31 MPa).More preferably, the cement composition has a transition time of lessthan 1 hr, using the SGSA static gel strength procedure at a temperatureof 155° F. (68.3° C.) and a pressure of 4,500 psi (31 MPa). Mostpreferably, the cement composition has a transition time of less than 30minutes (min), using the SGSA static gel strength procedure at atemperature of 155° F. (68.3° C.) and a pressure of 4,500 psi (31 MPa).In another embodiment, the cement composition has a transition time ofless than 70 min at the bottomhole temperature and pressure of thesubterranean formation.

Preferably, the cement composition has a transition time of less than 70minutes (min), using the Mini MACS static gel strength procedure at atemperature of 60° F. (15.6° C.) and a pressure of 5,000 psi (34.5 MPa).In one embodiment, the C-S-H seeds are in at least a sufficientconcentration such that the cement composition has a transition time ofless than 70 minutes (min), using the Mini MACS static gel strengthprocedure at a temperature of 60° F. (15.6° C.) and a pressure of 5,000psi (34.5 MPa). More preferably, the cement composition has a transitiontime of less than 50 min, using the Mini MACS static gel strengthprocedure at a temperature of 60° F. (15.6° C.) and a pressure of 5,000psi (34.5 MPa). Most preferably, the cement composition has a transitiontime of less than 30 min, using the Mini MACS static gel strengthprocedure at a temperature of 60° F. (15.6° C.) and a pressure of 5,000psi (34.5 MPa).

The cement composition can further include other additives. Examples ofother additives include, but are not limited to, a filler, a fluid lossadditive, a set retarder, a friction reducer, a strength-retrogressionadditive, a light-weight additive, a defoaming agent, a high-densityadditive, a mechanical property enhancing additive, a lost-circulationmaterial, a filtration-control additive, a thixotropic additive, andcombinations thereof.

The cement composition can include a filler. Suitable examples offillers include, but are not limited to, fly ash, sand, clays, andvitrified shale. Preferably, the filler is in a concentration in therange of about 5% to about 50% by weight of the cement (bwc).

The cement composition can include a fluid loss additive. Suitableexamples of commercially-available fluid loss additives include, but arenot limited to, and are marketed by Halliburton Energy Services, Inc.under the tradenames HALAD®-344, HALAD®-413, and HALAD®-300. Preferably,the fluid loss additive is in a concentration in the range of about0.05% to about 10% bwc.

The cement composition can include a set retarder. Suitable examples ofcommercially-available set retarders include, but are not limited to,and are marketed by Halliburton Energy Services, Inc. under thetradenames HR®-4, HR®-5, HR®-6, HR®-12, HR®-20, HR®-25, SCR-100™, andSCR-500™. Preferably, the set retarder is in a concentration in therange of about 0.05% to about 10% bwc.

The cement composition can include a friction reducer. Suitable examplesof commercially-available friction reducers include, but are not limitedto, and are marketed by Halliburton Energy Services, Inc. under thetradenames CFR-2™, CFR-3™, CFR-5LE™, CFR-6™, and CFR-8™. Preferably, thefriction reducer is in a concentration in the range of about 0.1% toabout 10% bwc.

The cement composition can include a strength-retrogression additive.Suitable examples of commercially-available strength-retrogressionadditives include, but are not limited to, and are marketed byHalliburton Energy Services, Inc. under the tradenames SSA-1™ andSSA-2™. Preferably, the strength-retrogression additive is in aconcentration in the range of about 5% to about 50% bwc.

The cement composition can include a light-weight additive. Suitableexamples of commercially-available light-weight additives include, butare not limited to, and are marketed by Halliburton Energy Services,Inc. under the tradenames SPHERELITE® and LUBRA-BEADS® FINE; andavailable from 3M in St. Paul, Minn. under the tradenames HGS2000™,HGS3000™, HGS4000™, HGS5000™, HGS6000™, HGS10000™, and HGS18000™ glassbubbles. Preferably, the light-weight additive is in a concentration inthe range of about 5% to about 50% bwc.

Commercially-available examples of other additives include, but are notlimited to, and are marketed by Halliburton Energy Services, Inc. underthe tradenames High Dense® No. 3, High Dense No. 4, Barite™, Micromax™,Silicalite™, WellLife® 665, WellLife® 809, WellLife® 810, and ChannelSeal™ Fluid.

In one embodiment, the cement composition has a density of at least 8pounds per gallon (ppg) (0.96 kilograms per liter (kg/l)). In anotherembodiment, the cement composition has a density of at least 15 ppg (1.8kg/l). In another embodiment, the cement composition has a density inthe range of about 8 to about 15 ppg (about 0.96 to about 1.8 kg/l). Inanother embodiment, the cement composition has a density in the range ofabout 15 to about 20 ppg (about 1.8 to about 2.4 kg/l).

According to certain embodiments, a method of cementing in asubterranean formation comprises: introducing a cement composition intothe subterranean formation, wherein the cement composition comprises:cement; water; and C-S-H seeds; and allowing the cement composition toset.

The method embodiments include the step of introducing the cementcomposition into a subterranean formation. The step of introducing isfor the purpose of at least one of the following: well completion; foamcementing; primary or secondary cementing operations; well-plugging;squeeze cementing; and gravel packing. The cement composition can be ina pumpable state before and during introduction into the subterraneanformation. In one embodiment, the subterranean formation is penetratedby a well. The well can be, without limitation, an oil, gas, water, orinjection well. According to this embodiment, the step of introducingincludes introducing the cement composition into the well. According toanother embodiment, the subterranean formation is penetrated by a welland the well includes an annulus. According to this other embodiment,the step of introducing includes introducing the cement composition intoa portion of the annulus.

The method embodiments can further comprise the step of forming thecement composition prior to the step of introducing. According to thisembodiment, the step of forming can comprise: adding at least thecement, the water, and the C-S-H seeds to a mixing apparatus; and mixingthe cement composition. The step of forming can further include addingat least one additive to form the cement composition. For example, alatex additive can be included to form the cement composition. The stepof adding can be performed in any order. For example, the C-S-H seedscan be added to the cement and then the water can be added to the cementand C-S-H seeds. By way of another example, the water can be added tothe cement and then the C-S-H seeds can be added to the water and thecement. By way of another example, the C-S-H seeds and the cement can beadded to the water at the same time. Regardless of the sequence ofadding, it is to be understood that the C-S-H seeds added to the cementcomposition are in addition to any C-S-H formed from the hydrationreaction between any of the phases of the cement and the water. If anyother additives, such as a latex additive, are to be included in thecement composition, then the other additive(s) can be added to thecement composition in any order. The step of mixing can be performedusing a suitable mixing apparatus.

The method embodiments can further include the step of determining themaximum PVF (Packing Volume Fraction) prior to the step of introducing.If the method embodiments further include the step of forming the cementcomposition, then the step of determining the maximum PVF is performedprior to the step of forming. The term “packing volume fraction” refersto the volume of the solid particulate materials in a fluid divided bythe total volume of the fluid. The size ranges of the preferred solidparticulate materials are selected, as well as their respectiveproportions, in order to provide a maximum (or close as possible tomaximum) packing volume fraction so that the fluid is in a hinderedsettling state. In order to obtain the maximum PVF, a combination of thefollowing three features can be used. The first is the use of at leastthree particulate materials wherein the at least three particulatematerials are in size ranges “disjointed” from one another. The secondfeature is the choice of the proportions of the three particulatematerials in relation to the mixing, such that the fluid, when mixed, isin a hindered settling state. The third feature is the choice of theproportions of the three particulate materials between each other, andaccording to their respective size ranges, such that the maximum PVF isat least substantially achieved for the sum total of all particulatematerials in the fluid system. The step of determining the maximum PVFcan further include the step of selecting the particle sizes of theC-S-H seeds and any other additives in order to attain the maximum PVF.The step of determining the maximum PVF and how to select the particlesizes can be found in U.S. Pat. No. 7,213,646 B2 issued to Craig W.Roddy, Ricky L. Covington, and Jiten Chatterji on May 8, 2007, which ishereby incorporated by reference in its entirety for all purposes.

The method embodiments also include the step of allowing the cementcomposition to set. The step of allowing can be after the step ofintroducing the cement composition into the subterranean formation. Themethod embodiments can include the additional steps of perforating,fracturing, or performing an acidizing treatment, after the step ofallowing.

The subterranean formation can have a bottomhole temperature in therange of about 35° F. to about 300° F. (about 1.7° C. to about 148.9°C.). Preferably, the subterranean formation has a bottomhole temperaturein the range of about 40° F. to about 190° F. (about 4.4° C. to about87.8° C.). More preferably, the subterranean formation has a bottomholetemperature in the range of about 60° F. to about 120° F. (about 15.6°C. to about 48.9° C.).

EXAMPLES

To facilitate a better understanding of the preferred embodiments, thefollowing examples of certain aspects of the preferred embodiments aregiven. The following examples are not the only examples that could begiven according to the preferred embodiments and are not intended tolimit the scope of the invention.

For the data contained in the following tables and figures, theconcentration of any ingredient in a cement composition can be expressedas, by weight of the cement (abbreviated as “bwc”) or gallons per sackof cement (abbreviated as “gal/sk”). The C-S-H seeds were X-SEED® 100,obtained from BASF. The C-S-H seeds were in a slurry form having 20%active solids. All of the concentrations of C-S-H seeds are expressedbased on the dry weight of the C-S-H seeds and do not take into accountthe weight of the continuous phase of the slurry. The dry weightconcentrations were calculated based on the 20% activity of the C-S-Hseeds in the slurry.

Unless otherwise stated, each of the cement compositions had a densityof 16.4 pounds per gallon (lb/gal) (1.97 kg/l) and contained at leastthe following ingredients: 4.92 gal/sk deionized water; Joppa Class Hcement or Dyckerhoff Class G cement; 0.05 gal/sk D-AIR 3000L™ defoamingagent; 0.05% bwc CFR-3™ friction reducer; and 0.05% bwc HR®61, setretarder. Any additional ingredients in the cement composition will beincluded for each table and listed as “additional ingredients.”

Unless stated otherwise, all of the cement compositions were mixed andtested according to the procedure for the specific test as described inThe Detailed Description section above. The cement compositions weretested for initial setting time at a variety of temperatures and apressure of 3,000 psi (21 MPa). The tests for time to reach 500 psi wereconducted at a variety of temperatures and a pressure of 3,000 psi (21MPa). The compressive strength tests were conducted at 24 or 48 hours, avariety of temperatures, and a pressure of 3,000 psi (21 MPa). Thethickening time tests were conducted at a variety of temperatures and apressure of 5,000 psi (34.5 MPa).

Table 1 contains time to reach 500 psi, compressive strength at 24hours, rate of compressive strength development, and thickening timedata for several cement compositions. The cement compositions alsocontained the following additional ingredients: varying concentrationsof C-S-H seeds (% bwc); and either LATEX® 2000 or LATEX® 3000 at aconcentration of 1 gal/sk. The cement compositions containing LATEX®2000, also included 0.2 gal/sk 434B™ latex stabilizer. As can be seen inTable 1, the cement compositions containing either 0.5% or 1% bwc C-S-Hseeds, exhibited improved physical properties compared to the cementcomposition that did not contain C-S-H seeds. The data in Table 1indicates that, for a given cement composition, as temperatureincreases, the physical properties of the cement composition areenhanced. For example, as temperature increases, the thickening timedecreases, the compressive strength increases, and the rate of strengthdevelopment increases. As can also be seen in Table 1, the physicalproperties of a cement composition can be improved with an increase inconcentration of C-S-H seeds. The data also shows that C-S-H seeds arenot only compatible with two different latex additives, but also improvethe physical properties of a cement composition containing the latexadditive.

TABLE 1 Conc. Rate of Strength Type of Time to 500 psi CompressiveDevelopment Thickening Time of C—S—H (hr:min) Strength (psi) (psi/hr)(hr:min) Latex seeds 80° F. 120° F. 190° F. 80° F. 120° F. 190° F. 80°F. 120° F. 190° F. 80° F. 120° F. 190° F. 2000 0 >40 49:28  19:52  0 201,417 — — 280 >20 >20 5:13 2000 0.5 17:28 12:20  7:00 980 2,016 2,795 72273 588 9:33 7:39 5:30 2000 1 13:16 8:22 3:54 2,145 2,485 2,472 160 119602 7:15 4:44 1:54 3000 0 >30 >30 20:03  10.6 14.2 2,196 — — 416.7 >2018:05  8:07 3000 0.5 13:50 8:43 6:53 2,165 3,416 2,772 130.5 384.7 60210:14  6:12 2:25 3000 1 14:42 8:07 4:22 2,141 3,193 3,109 137 333.3 9097:49 3:13 1:39

Table 2 contains transition time data for several cement compositions.The cement compositions were tested using the SGSA static gel strengthprocedure at a temperature of 155° F. (68.3° C.) and a pressure of 4,500psi (31 MPa). The cement compositions also contained the followingadditional ingredients: varying concentrations of C-S-H seed (1 bwc);and 1 gal/sk of either LATEX® 2000 or LATEX® 3000. As can be seen inTable 2, a cement composition containing a commonly-used latex additiveto help control gas migration has a transition time of at least threehours. With the addition of C-S-H seeds, the transition time can begreatly decreased. As can also be seen in Table 2, the transition timecan be decreased with an increase in concentration of the C-S-H seeds.

TABLE 2 Concentration of LATEX ® 2000 LATEX ® 3000 C-S-H TransitionTransition seeds Time (hr:min) Time (hr:min) 0 3:27 5:47 0.5 1:01 0:41 10:17 0:16

Table 3 contains thickening time, initial setting time, time to reach500 psi, and 24 hour compressive strength data for several cementcompositions. The cement compositions had a density of 15.8 ppg (1.9kg/l) and contained the following ingredients: 4.92 gal/sk deionizedwater; Dyckerhoff Class G cement; and varying concentrations of C-S-Hseeds (1 bwc). As can be seen in Table 3, for a given temperature, asthe concentration of C-S-H seeds increases, the thickening time, initialsetting time, and time to reach 500 psi is decreased, and thecompressive strength is increased. As can also be seen in Table 3, for agiven concentration of C-S-H seeds, temperature plays an important rolein the physical/mechanical properties of a cement composition. Forexample, as the temperature increases, the thickening time decreases andcompressive strength increases.

TABLE 3 Conc. of Thickening Initial Time to Compressive C-S-H Temp. TimeSetting Time 500 psi Strength seeds (° F.) (hr:min) (hr:min) (hr:min)(psi) 0.2 60 4:50 6:55 15:11 1,350 0.35 60 3:46 6:09 13:38 1,239 0.6 602:35 5:16 11:03 1,623 0.35 50 6:03 8:28 17:29 1,001 1.8 50 2:33 — — —

Table 4 contains zero gel time and transition time data for twodifferent cement compositions. The tests for the data contained in Table4 were performed to evaluate the effectiveness of C-S-H seeds in a lowdensity cement composition. The tests for zero gel time and transitiontime were performed using the “Mini MACS static gel strength” procedureat a temperature of 60° F. (15.6° C.) and a pressure of 5,000 psi (34.5MPa) and stirred for 4 hours. Cement composition number 1 had a densityof 15.8 ppg (1.9 kg/l) and contained: 4.90 gal/sk deionized water;Dyckerhoff Class G cement; and 0.35% bwc C-S-H seeds. Cement compositionnumber 2 had a density of 12.5 ppg (1.5 kg/l) and contained: 7.10 gal/skdeionized water; Dyckerhoff Class G cement; 3% bwc C-S-H seeds; and 30%bwc SPHERELITE® light-weight additive, available from Halliburton EnergyServices, Inc. As can be seen in Table 4, the two cement compositionshad comparable zero gel time and transition time. The data in Table 4indicates that an increase in concentration of C-S-H seeds may be neededas the density of a cement composition is decreased.

TABLE 4 Zero Gel Transition Cement Composition Time (hr:min) Time(hr:min) #1 4:02 0:06 #2 4:03 0:03

The tests for the data listed in Table 5 were conducted to evaluate theeffectiveness of C-S-H seeds compared to some commonly-used setaccelerators (namely a salt and a thixotropic additive). The cementcompositions contained: Dyckerhoff Class G cement; 4.9 gal/sk deionizedwater for the cement compositions with a density of 15.8 ppg; 7.63gal/sk deionized water for the cement compositions with a density of12.5 ppg (1.5 kg/l); varying concentrations of C-S-H seeds; and varyingconcentrations of calcium chloride (CaCl₂) or VersaSet thixotropicadditive. Table 5 contains thickening time, initial setting time, timeto reach 500 psi, and 24 hour and 48 hour compressive strength data forseveral cement compositions. As can be seen in Table 5, C-S-H seedsprovide comparable or slightly improved properties to a cementcomposition compared to a cement composition containing CaCl₂ orVersaSet. The C-S-H seeds provided a slightly longer thickening time,but a higher 24 hour compressive strength compared to the cementcomposition containing CaCl₂, even though the concentration of C-S-Hseeds was much less than the concentration of salt. The cementcomposition containing C-S-H seeds also exhibited higher 24 and 48 hourcompressive strength compared to the cement composition containingVersaSet. As can also be seen in Table 5, the C-S-H seeds can provideimproved properties to cement compositions having a density of around 12ppg and a density of around 16 ppg. This shows the compatibility andusefulness of C-S-H seeds in cement compositions having a wide range ofdensities.

TABLE 5 C—S—H Initial 24 hr. 48 hr. seeds Thick. Setting Time to Comp.Comp. Density Conc. CaCl₂ VersaSet Time Time 500 psi Strength Strength(ppg) (% bwc) (% bwc) (% bwc) (hr:min) (hr:min) (hr:min) (psi) (psi)15.8 0.07 0 0 6:03 8:28 17:29 1,001 1,863 15.8 0 1.8 0 4:31 9:10 18:28699 1,804 12.5 0.324 0 0 5:25 11:19  24:02 486 1,143 12.5 0 0 1.0 2:018:38 31:52 342 809

FIG. 1 is a graph of consistency (Bc) versus time (hr:min:sec) for fourdifferent cement compositions. Consistency testing was performed at atemperature of 60° F. (15.6° C.) for three of the cement compositionsand 50° F. (10° C.) for the other cement composition, and a pressure of5,000 psi (34.5 MPa). Each of the cement compositions had a density of15.8 ppg and contained deionized water, Class G cement, 0.05 gal/skD-AIR 3000L™ defoaming agent, and varying concentrations of C-S-H seeds(5 bwc). As can be seen in FIG. 1, the thickening time decreases with anincrease in concentration of C-S-H seeds. As can also be seen in FIG. 1,for a given concentration of C-S-H seeds, as the temperature decreases,the thickening time increases.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is, therefore, evident thatthe particular illustrative embodiments disclosed above may be alteredor modified and all such variations are considered within the scope andspirit of the present invention. While compositions and methods aredescribed in terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods also can “consistessentially of” or “consist of” the various components and steps.Whenever a numerical range with a lower limit and an upper limit isdisclosed, any number and any included range falling within the range isspecifically disclosed. In particular, every range of values (of theform, “from about a to about b,” or, equivalently, “from approximately ato b,” or, equivalently, “from approximately a to b”) disclosed hereinis to be understood to set forth every number and range encompassedwithin the broader range of values. Also, the terms in the claims havetheir plain, ordinary meaning unless otherwise explicitly and clearlydefined by the patentee. Moreover, the indefinite articles “a” or “an”,as used in the claims, are defined herein to mean one or more than oneof the element that it introduces. If there is any conflict in theusages of a word or term in this specification and one or more patent(s)or other documents that may be incorporated herein by reference, thedefinitions that are consistent with this specification should beadopted.

What is claimed is:
 1. A method of cementing in a subterranean formationcomprising: introducing a cement composition into the subterraneanformation, wherein the cement composition comprises: cement; water; andcalcium silicate hydrate (C-S-H) seeds, wherein a test cementcomposition consisting essentially of: the cement; the water; and theC-S-H seeds, and in the same proportions as in the cement composition,develops a compressive strength of at least 1,200 psi (8.3 MPa) whentested at 24 hours, a temperature of 60° F. (15.6° C.), and a pressureof 3,000 psi (20.7 MPa); and allowing the cement composition to set. 2.The method according to claim 1, wherein the cement comprises at leastone hydraulic cement selected from the group consisting of Portlandcement, pozzolana cement, gypsum cement, high alumina content cement,slag cement, silica cement, and combinations thereof.
 3. The methodaccording to claim 1, wherein the water is selected from the groupconsisting of freshwater, brackish water, saltwater, and any combinationthereof.
 4. The method according to claim 1, wherein the C-S-H seedshave a particle size distribution such that at least 90% of the C-S-Hseeds have a particle size in the range of 1 micron to 0.1 microns. 5.The method according to claim 1, wherein the C-S-H seeds are in aconcentration in the range of about 0.05% to about 7% by weight of thecement.
 6. The method according to claim 1, wherein the cementcomposition further comprises a latex additive.
 7. The method accordingto claim 6, wherein the latex additive is a slurry containing solidrubber particles as the dispersed phase and a liquid as the continuousphase.
 8. The method according to claim 7, wherein the rubber particlesare selected from the group consisting of: cis-1,4-polyisoprene rubber;styrene-butadiene rubber (SBR), high styrene resin; butyl rubber;ethylene-propylene rubbers (EPM and EPDM); neoprene rubber; nitrilerubber; silicone rubber; chlorosulfonated polyethylene rubber;crosslinked polyethylene rubber; epichlorohydrin rubber; fluorocarbonrubber; fluorosilicone rubber; polyurethane rubber; polyacrylic rubber;polysulfide rubber; AMPS-styrene-butadiene rubber; modified types of anyof the foregoing rubbers; and combinations thereof.
 9. The methodaccording to claim 1, wherein the cement composition has a thickeningtime in the range of about 4 to about 15 hours at a temperature of 60°F. (15.6° C.) and a pressure of 5,000 psi (34.5 MPa).
 10. The methodaccording to claim 1, wherein the cement composition has an initialsetting time of less than 24 hours at a temperature of 60° F. (15.6° C.)and a pressure of 3,000 psi (20.7 MPa).
 11. The method according toclaim 1, wherein the cement composition has a setting time of less than48 hours at a temperature of 60° F. (15.6° C).
 12. The method accordingto claim 1, wherein the cement composition has a compressive strength inthe range of about 1,000 to about 5,000 psi (about 3.5 to about 34.5MPa) when tested at 24 hours, a temperature of 60° F. (15.6° C), and apressure of 3,000 psi (20.7 MPa).
 13. The method according to claim 1,wherein the cement composition has a transition time of less than 1hour, using the SGSA static gel strength procedure at a temperature of155° F. (68.3° C) and a pressure of 4,500 psi (31 MPa).
 14. The methodaccording to claim 1, wherein the cement composition has a transitiontime of less than 50 minutes, using the Mini MACS static gel strengthprocedure at a temperature of 60° F. (15.6° C.) and a pressure of 5,000psi (34.5 MPa).
 15. The method according to claim 1, wherein the cementcomposition further includes at least one additive.
 16. The methodaccording to claim 15, wherein the at least one additive is selectedfrom the group consisting of a filler, a fluid loss additive, a setretarder, a friction reducer, a strength-retrogression additive, alight-weight additive, a defoaming agent, a high-density additive, amechanical property enhancing additive, a lost-circulation material, afiltration-control additive, a thixotropic additive, and combinationsthereof.
 17. The method according to claim 1, wherein the subterraneanformation has a bottomhole temperature in the range of about 60° F. toabout 120° F. (about 15.6° C. to about 48.9° C).
 18. The methodaccording to claim 1, further comprising the step of determining themaximum Packing Volume Fraction prior to the step of introducing.
 19. Amethod of cementing in a subterranean formation comprising: introducinga cement composition into the subterranean formation, wherein the cementcomposition comprises: cement; water; and calcium silicate hydrate(C-S-H) seeds, wherein the C-S-H seeds are in at least a sufficientconcentration such that the cement composition develops a compressivestrength of at least 1,200 psi (8.3 MPa) when tested at 24 hours, atemperature of 60° F. (15.6° C), and a pressure of 3,000 psi (20.7 MPa),whereas a substantially identical cement composition without the C-S-Hseeds, develops a compressive strength of less than 1,200 psi (8.3 MPa)when tested at 24 hours, a temperature of 60° F. (15.6° C.), and apressure of 3,000 psi (20.7 MPa); and allowing the cement composition toset.
 20. A method of cementing in a subterranean formation comprising:introducing a cement composition into the subterranean formation,wherein the cement composition comprises: cement; water; and calciumsilicate hydrate (C-S-H) seeds, wherein the C-S-H seeds are mesoscopicparticles, nanoparticles, or combinations thereof, and wherein the C-S-Hseeds are in a concentration in the range of about 1% to about 5% byweight of the cement; and allowing the cement composition to set.